1. Field of the Invention
Cefuroxime is an important antibiotic which has been used for many years in the therapy of gram-negative bacteria infections and is characterised by the formula (I)

It is administered as the sodium salt by intravenous and intramuscular injection.
The aforesaid formula (I) is clearly derived from the 7-ACA nucleus, which in the chemical synthesis process is subjected to a series of reactions which modify it in positions 3 and 7.
2. Discussion of the Background Art
According to the known art, the aforesaid sodium salt is prepared in injectable sterile form from an intermediate isolated from the aforesaid chemical synthesis process. The intermediate used in the known art is not the cefuroxime acid as would be logical to suppose, because it is very unstable to the extent of becoming visibly coloured after 30 days under vacuum at +5° C. Consequently, so far the background art has not used the non-sterile tetrahydrofuran solvated sodium salt, claimed for example in U.S. Pat. No. 4,277,601 and also cited in U.S. Pat. No. 4,775,750 column 1, line 51. The aforesaid intermediate is put into solution, sterilely filtered and reprecipitated to provide the injectable product.
In industrial practice, it is convenient to produce large batches of intermediate to be stored under suitable conditions, to then be used in small batches for producing the sterile sodium salt. It has however been observed that the stability of the tetrahydrofuran solvated sodium salt is not very high, even though higher than that of the acid as such, in particular because of a moisture content usually ≧2% which cannot be reduced in any way. It is therefore apparent that the intermediate cannot be stored at length without observing coloration and degradation which affect the yield and quality of the finished product.